You can easily find out what your fiances PSA test results are, but you need to be cute and ask the right questions.
The results are normally back at the GP's surgery within a couple of days of the test.
Every time I phone my GP's surgery and ask for the result the receptionist allways tells me my PSA was 'normal'.
I then have to say to her, 'there should be a number, what is the number?' and then she tells me.
Honestly it is like deja vue, Ground Hog day, exactly the same conversation every 3 months.
HT was explained to me like this, not exactly scientific but it helped me to understand it. Some of the cancer cells are dependent on testosterone others are not, so think your tumour as a bowl full of mixed peas and sweetcorn, the HT causes the sweetcorn to die but you are still left with the peas, so the tumour physically shrinks in size, just like the bowl would shrink when the sweet corn was taken out of it.
If as you say, your fiance has bone mets, these will be shrinking a bit too, this will be rearranging his internal geography and might be putting presure on the nerves causing him pain. Like Lyn said in her post you need to be aware that HT may be changing the internal pressure on the spine. So just like sciatica causes pain in the legs as the discs in our spine dry out and put pressure on the spinal cord, so bone mets may be shrinking on HT and putting presure on the nerves.
So I can only repeat Lyn's advice, you need to get in touch with specialist nurses / GP / Consultant as soon as possible.
Trouble is if you go anywhere near a hospital today, they will probablly admit your fiance and keep him in the Urology ward where there are all sorts of nasty infections waiting to be caught. So it's a judgement call, these things always seem to happen at bank holidays!
Best of luck.